In 1991, on a trip to London, I had some free time and went to the British Library. I saw a lot of manuscripts on display, but nothing on science. I asked a guard for directions to the scientific manuscripts, meaning some room where they might be on display. He seemed puzzled, but was very helpful. “What do you mean, sir?”

“Like Newton,” I said, feeling hopelessly American in a civilized country. “Isaac Newton,” I added for clarity.

“Ah,” he said. “Are you a scholar, sir?”

Tough question. I decided to throw modesty to the wind.  “Yes, I’m a professor in New York.”

He smiled and asked me to follow him, which seemed strange.  I thought, “Jeez, all I want to know is how to find the science section!”

We passed through a door, and entered a guarded corridor. The second guard, even more friendly than the first, was told that the American scholar was interested in seeing some manuscripts of Isaac Newton. I was brought into the manuscript reading room and given a bound book containing a large variety of letters, manuscripts, etc. from the 16^th century. Several pages were original manuscripts of Isaac Newton (in Latin) on ancient solar and lunar calendars, including a table of calculations. I actually had the original Isaac Newton manuscripts in my hand. When I was able to come to my senses, I realized what an incredible opportunity I had.

I looked up Darwin in the catalog, and found that there was a file of over 300 pages of correspondence between Darwin and Alfred Russel Wallace, famed naturalist and co-discoverer of evolution by natural selection. I was given the collection and began to go through it with all the reverence a priest would feel looking at an original manuscript written by the Apostle Paul.

Darwin’s letters were all handwritten on small quartered sheets (both sides of the paper) and many were not dated. Wallace’s letters were typed blue carbon copies. This told me that the collection had come from Wallace.

I leafed through these letters with a great deal of pleasure. Some of Darwin’s notes were barely legible, which didn’t surprise me, since I knew that during his fits of illness writing became difficult for him. I was skimming through some of the later letters when one caught my attention. It was written on a folded sheet of note paper with a black border.

The letter is short and it contains part of an ongoing discussion with Wallace about heredity. At that time no one knew anything about heredity or genes except Mendel, and Mendel’s work had been all but lost. Everything I had ever read about Darwin maintained that he believed, like everyone else, that inheritance of characteristics was like blending of paint colors, meaning that the characteristics of both parents are blended together in the children. Yet in this letter (dated 1867), Darwin writes (the following is the complete text of the letter as hand-written by Darwin):

My dear Wallace

After I had dispatched my last note, the simple explanation which you give had occurred to me, & seems satisfactory.

I do not think you understand what I mean by the non-blending of certain varieties. It does not refer to fertility; an instance will explain; I crossed the Painted Lady & Purple sweet-peas, which are very differently coloured vars, & got, even out of the same pod, both varieties perfect but none intermediate. Something of this kind I sho[uld] think must occur at first with your butterflies & the three forms of Lythrum; tho these cases are in appearance so wonderful, I do not know that they are really more so than every female in this world producing distinct male & female offspring. I am heartily glad that you mean to go on preparing your journal. Believe me – yours very sincerely Ch. Darwin

In other words, Darwin tells Wallace that he crossed two different color pea plants and got only one or the other color, but no blended, or in-between varieties. Darwin is describing quantum inheritance, or genes, and was in fact using the same methodology as Mendel. I read the letter over and over again. Darwin knew about genes. This was the first indication I or anyone else had seen that Darwin had some inkling about the real mechanism of genetic inheritance, and I thought that was pretty important.

I sent a copy of the letter to Richard Dawkins (whom I admired as a leading proponent of Darwinian evolution and a brilliant Darwin scholar), and he later discussed this letter (and kindly gave me credit for its discovery) in an essay to be found in The Devil’s Chaplain.

 The best part of the story is my imagining Charles Darwin sitting in Heaven and paying close attention to the literature of the past century. I am sure he has followed the development of the field of genetics with great satisfaction, since the research confirms and provides a firm framework for the reality of his theory of evolution by natural selection. But I also can imagine him being a bit frustrated by the fact that he was so close to seeing the whole truth himself. And the evidence of how close he came had been locked away in a single letter in the British Library for over a hundred years. As the person who had the honor and privilege of bringing this letter to light, I feel that Darwin’s spirit is smiling down on me. Nothing could top that.